Dual speed pump



D. E. HELMS DUAL SPEED PUMP Nov. 8, 1966 2 Sheets-Sheet 1 Filed July 13, 1964 mm N% Wm vm m,

INVENTOR.

DONALD E. HELMS By M 6 1% ATTORNEY D. E. HELMS DUAL SPEED PUMP Nov. 8, 1966 2 Sheets-Sheet 2 Filed July 13, 1964 INVENTOR. DONALD E HELMS ATTORNEY United States Patent 3,283,722 DUAL SPEED PUMP Donald E. Helms, RR. 1, Box 131, Brookville, Ind. Filed July 13, 1964, Ser. No. 382,192 12 Claims. (Cl. 103-37) This invention relates to a dual speed fluid pump and, more particularly, to a fluid pump capable of automatically adjusting between at least two operational speeds depending upon the load pressures encountered.

It is oftentimes desirable to operate a pump displacing fluid at a comparatively fast speed when low load pressures are encountered but nevertheless retain the capability of automatically operating at lower speeds of fluid displacement and developing substantially higher pressures when the load pressures encountered are higher. While attempts have been made in the past to accomplish this end, these attempts have never met with complete success and/ or have required unduly large and cumbersome equipment.

A dual speed pump is shown, for example, in U.S. Patent No. 2,625,796. It is to be noted however that this pump, while capable of operation at duel speeds, requires both high and low level fluid injection to the pump.

It is therefore an object of this invention to provide an improved dual speed fluid pump that is compact yet eflicient.

It is another object of this invention to provide a dual speed fluid pump that automatically adjusts between operational speeds depending upon load pressures encountered.

It is yet another object of this invention to provide a dual speed fluid pump that requires only a single fluid reservoir and yet is capable of automatic dual operation.

It is still another object of this invention to provide a dual speed fluid pump having a floating piston actuation of which provides high speed operation, said floating piston being by-passed for low speed operation.

It is yet another object of this invention to provide a dual speed pump having a floating piston with a by-pass conduit therein, said conduit having spring biased valve means therein for controlling automatic operation between the available dual speeds.

With these and other objects in view which will become apparent to one skilled in the art as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the herein disclosed invention may be included as come within the scope of the claims.

The accompanying drawings illustrate one complete example of the embodiment of the invention constructed according to the best mode so far devised for the practical application of the principles thereof, and in which:

FIGURE 1 is a side sectional view of the two speed fluid pump of this invention;

FIGURE 2 is a top sectional view of the dual speed pump of this invention;

FIGURE 3 is a front view of the dual speed pump of this invention; and

FIGURE 4 is a rear view of the dual speed pump of this invention.

Referring now to the drawings in which like numerals are used for like characters throughout, the numeral 6 indicates generally the dual speed pump of this invention. Pump 6, as shown best in FIGURE 1, includes an actuator 7 (shown as a handle herein for illustration purposes) and an actuating piston 8 mounted for reciprocal movement in cylinder, or chamber, 9 of pump body 10. As can be seen best in FIGURE 1, O ring 11 is provided to ice form a seal between the walls of the cylinder and piston 8. Cylinder 9 communicates with a second chamber, or cylinder, 12 by means of fluid conduit 13. Cylinder 12, in turn, communicates with a larger cylinder 14, cylinders 12 and 14 being, for example, of a one to two radius ratio as shown in FIGURE 1.

A floating piston 18 is received in cylinders 12 and 14. This piston has a first portion 19 of suitable cross section to be received in cylinder 12 and a second larger portion 20 of suitable cross section to be received' in cylinder 14. 0 rings 21 and 22 are provided to form a seal between the small and large portions of piston 18 and cylinders 12 and 14, respectively. As shown best in FIGURE 1, floating piston 18 has two conduits 23 and 24 therethrough, both of which have check valves 25 and 26, respectively, therein, said valves being biased to closed position by means of springs 27 and 28, respectively, which springs may be adjusted in tension as required by means of a collar threaded into the conduit near the end opposite the ball as shown in FIGURE 1.

As also shown in FIGURE 1, each check valve consists of a ball seating against a restricted opening near the end of each conduit, check valve 25 permitting passage of fluid only from cylinder 14 to cylinder 12 (when the fluid pressure differential is great enough to overcome the bias of spring 27), and check valve 26 permitting passage of fluid only from cylinder 12 to cylinder 14 (when the fluid pressure is great enough to overcome the bias of spring 28).

Pump body 10 includes an end portion 29 that is fastened to the main body portion by means of screws 30, sealing engagement being provided by 0 rings 31. End portion 29 has an inlet conduit 32 therein, which conduit includes a check valve 33 (ball 34 seating against the restricted opening in the conduit) biased closed by adjustable tension spring 35. As shown in FIGURE 1, inlet conduit 32 may open into passage 36 leading to a fluid reservoir 37.

End portion 29 also has an outlet conduit 39 therein, which conduit includes a check valve 40 (ball 41 seating against the restricted opening in the conduit) biased closed by adjustable tension spring 42. As shown in FIGURE 1, outlet conduit 39 opens into passage 43 leading to a load 44.

A transverse passage 46 in end portion 29 communicates with both inlet conduit 32 and outlet conduit 39. Passage 46 has a check Valve 47 therein with ball 48 seating against the restricted opening in the passage so that passage 46 permits fluid flow from the outlet conduit 39 to inlet conduit 32 and then only if check valve 47 is open. Ball 48 is maintained seated against the restricted opening in passage 46 by means of rod 49 within passage 46, rod 49 having one end engaging ball 48 and the other fastened to handle 50 extending from the top of end portion 29. As shown in FIGURE I, handle 50 is threaded into end portion 29 of valve body 10 at the upper end of passage 46 with sealing engagement being provided by O ring 5'1.

End portion 29 of valve body 10 has a circular groove 53 therein to receive one end of spring 54, the other end of which engages floating piston 18. As shown in FIG- URES l and 2, spring 54 is within chamber 14 and biases floating piston 18 in the direction opposite that of the working stroke imparted by actuating piston 8. A breather passage 55 communicating with chamber 14 behind the large portion 20 of piston 18 facilitates movement of piston 18.

As brought out hereinabove, the pump of this invention automatically changes speed, i.e., volume of fluid displaced, at a predetermined load pressure. Since the diameter of portion 20 of piston 18 is larger than actuating piston 8, the actuating piston will, of course, displace a lesser amount of fluid per stroke but deliver more pounds per square inch (p.s.i.) than the floating piston, which displaces more fluid per stroke but delivers proportionally less p.s.i. pressure. It is a feature of this invention that the larger piston is of the floating type, and hence need not be mechanically linked to the actuating piston, thus enabling the physical shape of the pump body to be made as required.

In operation and assuming that piston 8 is in the up position, fluid will initially be drawn into chamber 14 through inlet conduit 32 and into chamber 12 and passage 9 through inlet conduit 32 and conduit 23 in floating piston 18. When piston 8 is pushed downwardly, fluid is displaced from passage 9 to chamber 12 forcing the floating piston to move through a work stroke (to the right as shown in FIGURE 1) (assuming that the force is not great enough to unseat ball 26). The work stroke of floating piston 18 forces fluid through outlet conduit 39 and hence to load 44. So long as the load pressure remains below the pre-selected value, the floating piston will continue to provide a work stroke each time that piston 8 is depressed (the floating piston is returned to its normal position, shown in FIGURE 1, by the bias exerted thereon by spring 54 plus the pressure differential between chambers 12 and 14 when piston 8 is raised, the tension of spring 28 being great enough to insure return of floating piston 18 to normal position before the conduit is opened).

When the preselected load pressure is reached, the pump of this invention automatically switches from high speed to low speed by by-passing the floating piston so that work is performed thereafter only by the small piston 8. As the preselected load pressure is reached, the pressure within chamber 14 builds to the point where movement of floating piston 18 in the Working direction is resisted to such an extent that the pressure in passage 9 overcomes the spring bias on valve 26. This opens valve 26 and inactivates, or by-passes, floating piston 18 so that only piston 8 thereafter performs Work. As brought out hereinabove, while this work is performed at slower speed, larger p.s.i. pressures are developed.

As will be readily apparent, the particular load value at which the automatic speed switching occurs depends in large measure upon the force exerted by spring 28. Switching from fast to slow speed could occur during the first work stroke or at any succeeding stroke depending upon the load pressure value selected and the actual load encountered.

From the foregoing, it should be obvious that pistons 8 and 18 are chosen so that piston 8 is smaller in cross section than is the larger protion of the floating piston. It is also to be realized that the invention is not meant to be limited to only two speeds of operation, since additional floating pistons could be added as would be obvious to one skilled in the art to provide additional operational speeds. It should also be noted that since there is no mechanical linkage between the pistons and since the floating piston is by-passed during slow speed operation, energy is conserved.

Assuming that the large portion of floating piston 18 has a two inch diameter, that the small portion has a three-fourth inch diameter, and that actuating piston 8 also is three-fourth inch in diameter and has a one inch work stroke, floating piston 18 will be moved one inch during the work stroke of actuating piston 8 during the high speed stroke, or cycle. Movement of the floating piston one inch will displace approximately 3.142 cubic inches of fluid during the high speed cycle, which fluid, of course, is fed through outlet conduit 39 and passage 43 to load 44. During the slow speed cycle, that is, when the floating piston is by-passed, the one inch stroke of actuating piston 8 displaces .442 cubic inch of fluid, and since the floating piston is by-passed, this fluid is directly coupled through conduit 24, chamber 14-, outlet conduit 39 and passage 43 to load 44. The ratio of this dual speed pump having pistons of the particular dimensions set forth hereinabove is approximately 7 to 1 but, as also brought out hereinabove, the ratio can be changed as desired by proper selection of piston diameters, as would be obvious to one skilled in the art and the invention is not meant to be limited to the particular dimensions expressed.

When it is desired to free the load pressure, release arm 58 is turned to raise rod 49. This permits valve 47 to open and allows the fluid to flow back to reservoir 37 through passage 36.

In view of the foregoing, it should be obvious to those skilled in the art that the pump of this invention provides an improved dual speed pump having automatic operational speed switching, requires no mechanical linkage between pistons, and yet is simple, compact and efiicient.

What is claimed as my invention is:

1. A rnulti-speed fluid pump comprising: a pump body having at least first and second chambers, said first chamber being smaller in cross section than said second chamber and said first chamber having at least first and second communicating portions; a first piston having at least first and second portions received in one portion of said first chamber and in said second chamber, respectively; a second piston received in the other portion of said first chamber; first valve equipped fluid inlet conduit means communicating with said first chamber between said first and second pistons; second valve equipped fluid inlet conduit means communicating with said second chamber at the side of said first piston opposite that of said second piston; valve equipped fluid outlet conduit means communicating With said second chamber at the same side of said second piston as is said second (inlet conduit means, said outlet conduit means being adapted to be connected to a load; valve equipped fluid by-pass conduit means communicating with said first chamber between said first and second pistons and being connected so as to permit conduction of fluid from said first chamber to said fluid outlet conduit means when a load attached to said output conduit means exceeds a predetermined pressure; and actuating means operatively connected to said second piston for actuation thereof, actuation of said sec-0nd piston actuating said first piston except when said predetermined load pressure is exceeded whereby said pump speed is automatically determined by the load pressure encountered.

2. The multi-speed fluid pump of claim 1 wherein said first piston is a spring biased integrally formed floating piston actuation of which is in a direction overcoming said spring bias thereon.

3. The multi-speed fluid pump of claim 1 wherein said first inlet conduit means is in said first piston and connects said second chamber to said first chamber for unidirectional passage of fluid from said second chamber to said first chamber.

4. The multi-speed fluid pump of claim 1 wherein said bypass conduit means is in said first piston for unidirectional passage of fluid from said first chamber through said second chamber to said fluid outlet conduit means.

5. The multi-speed pump of claim 4 wherein said bypass conduit means includes'adjustable tension spring biased valve means for maintaining said by-pass conduit means closed until a predetermined pressure is reached in said second chamber.

6. The multi-speed fluid pump of claim 1 wherein said actuating means repeatedly actuates said second piston and said second piston repeatedly actuates said first piston until said predetermined load pressure is reached, after which said first piston is bypassed by means of said by-pass conduit means so long as said predetermined pressure is exceeded.

7. A dual speed fluid pump comprising: a pump body having at least first and second cylinders therein, one portion of said first cylinder and said second cylinder being substantially coaxially positioned with the diameter f said 0 6 Portion of said first cylinder being smaller than that of said second cylinder; a floating piston having first and second portions received in one portion of said first cylinder and in said second cylinder, respectively, sealingly engaging the walls thereof; an actuating piston in the other portion of said first cylinder; first valve equipped inlet conduit means communicating with said first cylinder between said pistons; second valve equipped inlet conduit means communicating with said second cylinder at the side of said floating piston remote from said actuating piston, said inlet conduit means being adapted for connection to a fluid reservoir; valve equipped outlet conduit means communicating with said second cylinder at the same side of said floating piston as is said second inlet conduit means, said outlet conduit means being adapted to be connected to a load; valve equipped by-pass conduit means communicating with said first cylinder between said pistons and with said second cylinder at the same side of said floating piston as is said outlet conduit means, said by-pass conduit means permitting conduction of fluid from said first cyinder and bypassing said floating piston whenever a load attached to said outlet conduit means exceeds a predetermined pressure; and actuating means connected to said actuating piston, actuation of said actuating piston actuating said floating piston except when said predetermined load pressure is exceeded whereby the operational speed of said pump is automatically determined by load pressure.

8. The dual speed fluid pump of claim 7 wherein said floating piston has said first inlet conduit means therein and connects said cylinder for unidirectional conduction of fluid from said second cylinder to said first cylinder.

9. The dual speed fluid pump of claim 7 wherein said by-pass conduit means is in said floating piston for connecting said cylinders and permits unidirectional conduction of fluid from said first cylinder to said second cylinder but only when a predetermined load pressure is exceeded.

10. The dual speed fluid pump of claim 9 wherein said valve in said bypass conduit means is spring biased and determines said predetermined load pressure to be exceeded before said bypass conduit means is opened.

11. The dual speed fluid pump of claim 7 wherein said actuating means repeatedly actuates said actuating piston to repeatedly actuate said floating piston until said predetermined load is reached and to thereafter bypass the floating piston so long as said predetermined load pressure is exceeded.

12. A dual speed fluid pump comprising: a pump body having at least first and second cylinders therein, one portion of said first cylinder and said second cylinder being coaxially positioned communicating cylinders, the diameter of said one portion of said first cylinder being smaller than that of said second cylinder; a floating pis ton having integrally formed first and second portions, each of said portions being received in the adjacent ends of said one portion of said first cylinder and said second cylinder, respectively, and sealingly engaging the Walls thereof, said floating piston having a first valve equipped conduit therein for unidirectional conduction of fluid from said second cylinder to said first cylinder and a by-pass valve equipped conduit therein for unidirectional conduction of fluid from said first cylinder to said second cylinder; biasing means for maintaining said by-pass conduit valve closed until the pressure in said second cylinder exceeds a predetermined value; an actuating piston in said first cylinder; a valve equipped inlet conduit communicating with said second cylinder at the side of said floating piston remote from said actuating piston, said inlet conduit being connected to a fluid reservoir; a valve equipped outlet conduit communicating with said second cylinder at the same side as said inlet conduit, said outlet conduit being connected to a load; and actuating means connected to said actuating piston.

References Cited by the Examiner UNITED STATES PATENTS 2,435,326 2/1948 Schwerin 103-37 LAURENCE V. EFNER, Primary Examiner. 

1. A MULTI-SPEED FLUID PUMP COMPRISING: A PUMP BODY HAVING AT LEAST FIRST AND SECOND CHAMBERS, SAID FIRST CHAMBER BEING SMALLER IN CROSS SECTION THAN SAID SECOND CHAMBER AND SAID FIRST CHAMBER HAVINT AT LEAST FIRST AND SECOND COMMUNICATING PORTIONS; A FIRST PISTON HAVING AT LEAST FIRST AND SECOND PORTIONS RECEIVED IN ONE PORTION OF SAID FIRST CHAMBER AND IN SAID SECOND CHAMBER, RESPECTIVELY; A SECOND PISTON RECEIVED IN THE OTHER PORTION OF SAID FIRST CHAMBER; FIRST VALVE EQUIPPED FLUID INLET CONDUIT MEANS COMMUNICATING WITH SAID FIRST CHAMBER BETWEEN SAID FIRST AND SECOND PISTONS; SECOND VALVE EQUIPPED FLUID INLET CONDUIT MEANS COMMUNICATING WITH SAID SECOND CHAMBER AT THE SIDE OF SAID FIRST PISTON OPPOSITE THAT OF SAID SECOND PISTON; VALVE EQUIPPED FLUID OUTLET CONDUIT MEANS COMMUNICATING WITH SAID SECOND CHAMBER AT THE SAME SIDE OF SAID SECOND PISTON AS IS SAID SECOND INLET CONDUIT MEANS, SAID OUTLET CONDUIT MEANS BEING ADAPTED TO BE CONNECTED TO A LOAD; VALVE EQUIPPED FLUID BY-PASS CONDUIT MEANS COMMUNICATING WITH SAID FIRST CHAMBER BETWEEN SAID FIRST AND SECOND PISTONS AND BEING CONNECTED S AS TO PERMIT CONDUCTION OF FLUID FROM SAID FIRST CHAM- 